System and method for protocol conversion using facilities and utilities

ABSTRACT

A protocol converter ( 14 ) allows communications between a host ( 12 ) and remotes ( 16, 18, 20 ) that operate using different communications protocols. The protocol converter ( 14 ) includes processes ( 50 ) and subsystems ( 60 ) for establishing a communications session between the remotes ( 16, 18, 20 ) and the host ( 12 ). The processes include a session manager ( 52 ), a set of facilities ( 54 ), and a set of utilities ( 56 ). The subsystems include a logon subsystem ( 62 ), a communications subsystem ( 64 ), and a translator subsystem ( 66 ).

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.08/582,536 filed Jan. 3, 1996 and entitled “System and Method forProtocol Conversion Using Facilities and Utilities”, now U.S. Pat. No.6,405,254.

TECHNICAL FIELD OF THE INVENTION

This invention relates in general to communications, and moreparticularly to a protocol converter apparatus and method.

BACKGROUND OF THE INVENTION

A communications system includes a collection of interconnected devices.Often these devices communicate data using different protocols. Forexample, a remote that communicates data in a first protocol may desireto access a host that communicates data in a second protocol. A protocolconverter may be used to allow communications between the remote and thehost.

As communications systems become larger and more complex to serve avariety of devices, protocol converters should adapt to service anever-increasing number of communications protocols. Hardware-basedprotocol converters are difficult to adapt to service new protocols.Current software-based protocol converters often suffer from a lack ofmodular design, an inflexible and unreliable hardware/softwareinterface, and an inability to adapt quickly and efficiently to new andchanging communications protocols.

SUMMARY OF THE INVENTION

In accordance with the present invention, the disadvantages and problemsassociated with protocol converters in a communications system have beensubstantially reduced or eliminated.

In accordance with one embodiment of the present invention, acommunications system includes a remote that transmits first data in afirst protocol and a host that receives second data in a secondprotocol. A protocol converter coupled to the remote and the hostreceives first data from the remote. The protocol converter includes afirst facility, a utility, and a second facility running as processes onthe protocol converter. The first facility communicates first data tothe utility, the utility translates first data into second data, and thesecond facility communicates the second data to the host.

Important technical advantages of the present invention include aprotocol converter with a modular design to adapt quickly andefficiently to new and changing communications protocols. This modulardesign is provided by software processes called facilities andutilities. A facility provides support for a specific link layercommunications protocol, whereas a utility provides translation betweenhigher level protocols. In a particular embodiment, utilities may becascaded to provide layered protocol support.

Another important technical advantage includes managing thecommunications between facilities and utilities. In one embodiment, acommunications subsystem maintains a process table having an entry foreach process running on the protocol converter. In this manner,functions between utilities and facilities are isolated, processinterfaces are clearly defined and robust, and the hardware/softwareinterface in the protocol converter is accurately defined and reliablymaintained. Other important technical advantages of the presentinvention include a session manager that spawns facilities andutilities, a logon subsystem, and a translator subsystem. Othertechnical advantages are readily apparent to one skilled in the art fromthe following figures, descriptions, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and forfurther features and advantages, reference is now made to the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 illustrates a communications system having a protocol converter;

FIG. 2 illustrates a simplified block diagram of the operation of theprotocol converter;

FIGS. 3A and 3B are a flow chart of a method for establishing acommunications session using the protocol converter; and

FIG. 4 is a flow chart of a method to manage communications among theprocesses running on the protocol converter.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a communications system 10 that includes a host 12, aprotocol converter 14, and a plurality of remotes 16, 18, and 20. Host12 and remotes 16, 18, and 20 may operate using different communicationsprotocols. A protocol is generally any format, definition, orspecification for the communication of data, whether implemented insoftware, hardware, or both. A protocol may include, without limitation,transmission rates, frame formats, blocking formats, text formats,stop/start indicators, framing and heading indicators, fielddefinitions, checksum values, carriage return and line feed (CR/LF)indicators, and any other suitable information that specifies thecontent or nature of the transmitted data. In general, protocolconverter 14 establishes communications sessions that allow host 12 andremotes 16, 18, and 20 to exchange data.

Host 12 comprises a memory 22 and a processor 24 that together operateto store, process, or manipulate data. Memory 22 and processor 24 arecoupled to an interface 26 using bus 28. Interface 26 of host 12 couplesto interface 30 of protocol converter 14 using link 28. Generally, host12 may be any processing device coupled to any suitable wireline orwireless link 28 to communicate data with other processing devices. Inone particular embodiment, host 12 comprises a main frame computer andlink 28 communicates data using the IBM 3770 communications protocol.

Remotes 16, 18, and 20 each include a memory 32 and a processor 34 thattogether operate to store, process, or manipulate data. Memory 32 andprocessor 34 of remotes 16, 18, and 20 are coupled to an interface 36using bus 38. Interfaces 36 for remotes 16, 18, and 20 couple tointerface 40 of protocol converter 14 using links 42, 44, and 46,respectively. Generally, remotes 16, 18, and 20 may be any processingdevice coupled to any suitable wireline or wireless link 42, 44, and 46,respectively, to communicate data with other processing devices. Forexample, remotes 16, 18, and 20 may be mainframes, mini-frames, orpersonal computers and links 42, 44, and 46, respectively, communicatedata using ASYNC, BISYNC, SDLC/SNA, X.25, TCP/IP, X.400, or any suitablecommunications protocol. For example, the ASYNC family of protocols mayinclude specific implementations, such as XMODEM, YMODEM, ZMODEM,KERMIT, or other standards of asynchronous data communications.

As described above, protocol converter 14 couples to host 12 usinginterface 30 and to remotes 16, 18, and 20 using interface 40. In aparticular embodiment, interface 30 comprises IBM host LUA hardware thatimplements the IBM communications manager. Interface 30 may also be anyother suitable hardware that supports token ring, leased line, orswitched line communications between protocol converter 14 and host 12.In a particular embodiment, interface 40 comprises one or more real-timeinterface coprocessors (RTIC) cards that implement any suitablesynchronous, asynchronous, or other communications protocol betweenremotes 16, 18, and 20 and protocol converter 14.

Interfaces 30 and 40 are coupled to and interact with processes 50 andsubsystems 60 of protocol converter 14. Processes 50 include a sessionmanager 52, a set of facilities 54, and a set of utilities 56.Subsystems 60 include a logon subsystem 62, a communications subsystem64, and a translator subsystem 66. Logon subsystem 62 is coupled to alogon database 68 that stores configuration data and logon definitionsfor users of protocol converter 14. Communications subsystem 64 iscoupled to a process table 70 that maintains a list of processes 50running on protocol converter 14. In a particular embodiment, subsystems60 are dynamically linked libraries (DLLs) that are accessed using anapplication programmer interface (API).

An important technical advantage of protocol converter 14 is the use offacilities 54 and utilities 56 running as software processes on protocolconverter 14. Protocol converter 14 maintains a set of facilities 54,each designed to support a specific link layer or line layercommunications protocol, such as ASYNC, BISYNC, X.25, and others. In aparticular embodiment, facilities 54 support an ASYNC passthroughprotocol that passes data to utilities 56 with a minimum of alteration.Utilities 56 may then provide much of the protocol conversion of the rawASYNC passthrough data in software, which provides greater flexibilityfor supporting new protocols. If a link layer protocol is changed or anew link layer protocol is added, additional facilities 54 may bewritten or existing facilities 54 may be modified to add additionalfunctionality to protocol converter 14.

Protocol converter 14 also maintains a set of utilities 56 that providehigher level protocols, such as TCP/IP, XMODEM, YMODEM, ZMODEM, andKERMIT, as well as conversion, translation, formatting, or otherinterfacing functions between two facilities 54 in a communicationssession. Furthermore, utilities 56 may be written to provide customizedcommunications sessions associated with individual users, groups ofusers, or specific devices in communications system 10. Additionalutilities 56 may be written or existing utilities 56 modified to addfunctionality to protocol converter 14.

Utilities 56 may also be cascaded to provide layered protocol support.For example, a typical TCP/IP communications session between remote 16and protocol converter 14 may be supported by a single ASYNC facilityand several cascaded or layered utilities. In such a session, the lowestlevel ASYNC facility receives data from remote 16 and communicates thedata to an Internet protocol (IP) utility. The IP utility thencommunicates the data to a transport communication protocol (TCP)utility, which in turn communicates the data to the highest level filetransfer protocol (FTP) utility. Similarly, data communicated fromprotocol converter 14 to remote 16 passes through FTP utility, TCPutility, IP utility, and ASYNC facility. In this manner, utilities 56may be arranged in layers to provide a flexible and powerful protocolconversion function. It should be understood that utility 56 may referto a single utility or a collection of cascaded or layered utilities.

Both facilities 54 and utilities 56 operate as software processes withdefined functions and data interfaces that provide a modular softwaredesign that promotes debugging and modification of protocol converter14. By spawning, linking, and layering facilities 54 and utilities 56,session manager 52 can reliably construct a variety of communicationssessions in protocol converter 14.

Protocol converter 14 may operate on one or more computers, showngenerally as computer 72. Computer 72 maintains and executes theinstructions to implement processes 50 and subsystems 60. Computer 72may include an input device 74, such as a keypad, touch screen, or otherdevice that can accept information. Output device 76 conveys informationassociated with the operation of protocol converter 14, includingdigital or analog data, visual information, or audio information. Bothinput device 74 and output device 76 may include fixed or removablestorage media, such as a magnetic computer disk, CD-ROM, or othersuitable media to both receive output from and provide input to protocolconverter 14. Processor 78 and its associated volatile or non-volatilememory execute instructions and manipulate information in accordancewith the operation of protocol converter 14.

In operation, protocol converter 14 establishes a communications sessionbetween two or more devices using different communications protocol. Inone example, remote 16 may desire to communicate with host 12. Remote 16communicates data at a first protocol to interface 40 of protocolconverter 14 using link 42. Interface 40 then passes this data toselected facilities 54 and utilities 56 to accomplish conversion of thedata to a second protocol. The data in the second protocol is thenpassed to interface 30, which in turn passes the data in the secondprotocol to host 12 using link 28.

During communications between remote 16 and host 12, session manager 52spawns processes 50, including selected facilities 54 and utilities 56.Communications subsystem 64 maintains a list of spawned processes 50 inprocess table 70 to manage communications among processes 50. Logonsubsystem 62 receives logon information from remote 16 and accessesconfiguration data and logon definitions from logon database 68. Thisinformation may be used to select and/or configure processes 50 thatestablish the communications session between remote 16 and host 12. Thetranslator subsystem 66 may be utilized by processes 50 to perform dataconversions.

FIG. 2 illustrates a simplified block diagram of the operation ofprotocol converter 14 to establish a communications session betweenremote 16 and host 12. This communications session utilizes processes 50and subsystems 60. Although FIG. 2 describes the communications sessionas originating from remote 16 and terminating at host 12, it should beunderstood that the present invention contemplates unidirectional orbidirectional communications originated from any processing device incommunications system 10 and terminating at any other processing device.

Data in a first protocol from remote 16 is received at interface 40 ofprotocol converter 14. Interface 40 passes the data to facility 100which supports the link layer communications protocol utilized by remote16. Facility 100 communicates the content or existence of the receiveddata to session manager 102 which spawns utility 104. Facility 100 thencommunicates data to utility 104. In a particular embodiment, sessionmanager 102 may spawn an additional utility 106 which couples to utility104. Utility 106 communicates data to facility 108 which supportscommunication of data in a second link layer protocol utilized by host12. Facility 108 then communicates data in the second protocol tointerface 30 for delivery to host 12. Utility 104, utility 106, or bothmay be comprised of several cascaded or layered utilities.

In one embodiment, utilities 104 and 106 may be a single utility spawnedby session manager 102, as indicated by dashed line 109. If utilities104 and 106 are separate utilities spawned by session manager 102, thenutility 104 may translate data received from facility 100 in a firstprotocol into raw data for delivery to utility 106. Raw data may be anysuitable generic representation of data that is communicated betweenutilities. This raw data may be coupled to other utilities 110 fortranslation and delivery to other devices. In addition, the output ofutility 106 may be coupled to other facilities 112 for delivery tointerface 30, interface 40, or other interface circuitry of protocolconverter 14. For example, one of the other facilities 112 may couple toa portion of interface 40 to deliver data in a first protocol fromremote 16 to data in a second protocol to remote 18, remote 20, or both.

During the establishment of a communications session between remote 16and host 12, communications subsystem 64 generates a process table 70that includes an entry for processes 50 running on protocol converter14. Processes 50 may be entered into process table 70 as thecommunications session is established or may already be entered uponpower up or initialization of protocol converter 14. Each entry inprocess table 70 includes a process name 120, a process ID 122, data124, and a semaphore 126.

For the particular embodiment of FIG. 2, process table 70 includes thefollowing entries to support the communications session between remote16 and host 12: facility 100, session manager 102, utility 104, utility106, and facility 108. Each entry is given a separate identifier 122that is used in messaging between processes 50. For example, a messagesent from facility 100 to utility 104 may specify its source process ID122 as “1” and its destination process ID 122 as “3”. Communicationssubsystem 64 operates to control the messaging between processes 50, asdescribed in more detail below with reference to FIG. 4.

Logon subsystem 62 coupled to logon database 68 is accessible by allprocesses 50 to retrieve configuration data and logon definitions forusers of protocol converter 14. For example, logon database 68 mayinclude a logon definition that specifies utility 104 to be spawned bysession manager 102 upon reception of data from remote 16. Logondatabase 68 may also include a second or outgoing logon definition forremote 16 that specifies utility 106 or other utilities 110 to bespawned by session manager 102 for completing the communicationssession. In this manner, logon subsystem 62 can maintain separateincoming and outgoing logon definitions that are associated with a firstcommunications link between remote 16 and protocol converter 14 and asecond communications link between protocol converter 14 and host 12.These logon definitions may be combined to establish a variety ofcommunications session between devices in communications system 10. Inaddition, logon subsystem 62 may retrieve information from logondatabase 68 to validate a user name and password provided by remote 16,or to access or process other account information of remote 16.

Translator subsystem 66 may be accessed by utilities 104, 106, and 110to provide data translation. For example, utility 104 may desire data tobe translated from ASCII format into an IBM-compatible format, such asEBCDIC. In addition, translator subsystem 66 may also be utilized byutilities 104, 106, and 110 to manipulate records separation, such ascarriage return and line feed information, and to provide otherformatting of data. Therefore, translator subsystem 66 comprises a setof commonly accessible routines that perform a specific operation ondata.

FIGS. 3A and 3B are a flow chart of a method for establishing acommunications session between remote 16 and host 12. The method beginsat step 200 where a first interface 40 receives data from remote 16. Thedata is transferred to first facility 100 at step 202. First facility100 then sends a message to session manager 102 at step 204 indicatingthat first facility 100 has received data from or otherwise establishedcommunications with remote 16. At this point, session manager 102 mayproceed using two different embodiments, as indicated collectively bysteps 205 or 221.

In one embodiment using steps 205, session manager 102 spawns firstutility 104 at step 206 in response to the message received from firstfacility 100. At step 208, session manager 102 sends a message to firstutility 104 with the message source designated as first facility 100. Inresponse, first utility 104 sends an acknowledgment to first facility100 at step 210. In this manner, session manager 102 utilizes the sourceaddress of the message sent to first utility 104 to establishcommunications between first facility 100 and first utility 104. Firstutility 104, now coupled with first facility 100, receives logoninformation from remote 16 at step 212. At step 214, first utility 104accesses logon subsystem 62 to validate logon information received fromremote 16. If the logon information is not validated at step 214, thenthe communications session is terminated at step 216.

In another embodiment using steps 221, session manager 102 receiveslogon information from first facility 100 at step 220. At step 222,session manager 102 accesses logon subsystem 62 and logon database 68 tovalidate logon information received from remote 16. If the logoninformation is not validated at step 222, then the communicationssession is terminated at step 224. If the logon information is validatedat step 222, then session manager 102 spawns first utility 104 at step226 in response to the logon information. For example, the logoninformation received by session manager 102 from remote 16 or logondatabase 68 may specify a particular utility 104 to be utilized in thecommunications session between remote 16 and host 12. At step 228,session manager 102 sends a message to first utility 104 with themessage source designated as first facility 100. First utility 104 sendsan acknowledgment to first facility 100 at step 230. This acknowledgmentof the message received from session manager 102 establishescommunications between first facility 100 and first utility 104.

After spawning first utility 104 using steps 205 or steps 221, sessionmanager 102 may spawn second utility 106. These steps designatedcollectively as steps 240 are optional if the communications sessionbetween remote 16 and host 12 does not utilize second utility 106. Ifsecond utility 106 is utilized in the communications session, thensession manager 102 spawns second utility in response to logoninformation at step 242. For example, logon information received fromremote 16 or retrieved using logon subsystem 62 and logon database 68may specify second utility 106 to be utilized in the communicationssession. At step 244, session manager 102 sends a message to secondutility 106 with the message source designated as first utility 104.Second utility 106 sends an acknowledgment to first utility 104 at step246. This acknowledgment of the message received from session manager102 establishes communications between first utility 104 and secondutility 106.

Second facility 108 receives data from first utility 104 or secondutility 106 at step 248, depending on whether the communications sessionbetween remote 16 and host 12 utilizes second utility 106. Secondfacility 108 transfers this data to second interface 30 at step 250.Second interface 30 establishes communications with host 12 at step 252,and the establishment of the communications session between remote 16and host 12 is complete.

FIG. 4 is a flow chart of a method to manage communications of messagesamong processes 50 running on protocol converter 14. In the embodimentof FIG. 2, this method manages communications among the followingprocess 50: facility 100, session manager 102, utility 104, utility 106,and facility 108. The method begins at step 300 where a first processinforms communications subsystem 64 that it has data for a secondprocess. This data may be a message, instruction, response,acknowledgment, or any other information to be communicated from thefirst process to the second process.

Communications subsystem 64 posts data in data field 124 of processtable 70 associated with the second process at step 302. Communicationssubsystem 64 sets semaphore 126 of process table 70 associated with thesecond process at step 304. The second process then detects the settingof its associated semaphore 126 and receives data stored in itsassociated data field 124 at step 306.

In one embodiment, the second process may process the data and generateother data for a third process at step 308. The second process informscommunications subsystem 64 that it has data for the third process atstep 310. Communications subsystem 64 posts data in the data field 124of process table 70 associated with the third process at step 312.Communications subsystem 64 sets semaphore 126 of process table 70associated with the third process at step 314. The third process thendetects its associated semaphore 126 and receives data from itsassociated data field 124 at step 316. In this manner, communicationssubsystem 64 utilizing process table 70 is able to strictly andconsistently manage communications between separate processes 50 runningon protocol converter 14.

Although the present invention has been described with severalembodiments, a myriad of changes, variations, alterations,transformations, and modifications may be suggested to one skilled inthe art, and it is intended that the present invention encompass suchchanges, variations, alterations, transformations, and modifications asfall within the spirit and scope of the appended claims.

What is claimed is:
 1. A communications system comprising: a remoteoperable to transmit first data in a first protocol; a host operable toreceive second data in a second protocol; and a protocol convertercoupled to the remote and the host, the protocol converter operable toreceive the first data from the remote, the protocol convertercomprising a first facility, a second facility , and a session manageroperable to spawn a utility in response to receiving the first data, theutility operable to run as a process on the protocol converter and totranslate the first data into the second data, the first facilityoperable to communicate the first data to the utility, and the secondfacility operable to communicate to the host the second data translatedfrom the first data by the utility.
 2. The communications system ofclaim 1, wherein the utility comprises: a first utility operable toreceive the first data from the first facility and to translate thefirst data into raw data; and a second utility operable to receive theraw data from the first utility and to translate the raw data into thesecond data.
 3. The communications system of claim 1, wherein theprotocol converter comprises: a communications subsystem operable tomanage communications among the processes running on the protocolconverter; and a process table coupled to the communications subsystem,the process table having an entry for each process running on theprotocol converter.
 4. The communications system of claim 1, wherein:the first facility supports at least one of a first link layer and afirst line layer communications protocol; the second facility supportsat least one of a second link layer and a second line layercommunications protocol; and the utility is operable to translate thefirst data using the at least one of the first link layer and the firstline layer communications protocol into the second data using the atleast one of the second link layer and the second line layercommunications protocol.
 5. A protocol converter for communicating databetween a remote and a host, the protocol converter comprising: a firstfacility operable to receive first data in a first protocol from theremote; a plurality of cascaded utilities coupled to the first facilityand operable to receive the first data from the first facility, theplurality of cascaded utilities operable to translate the first datainto second data in a second protocol; and a second facility coupled tothe plurality of cascaded utilities, the second facility operable toreceive the second data from the plurality of cascaded utilities and tocommunicate the second data to the host.
 6. The protocol converter ofclaim 5, wherein the plurality of cascaded utilities comprises: a firstutility operable to receive the first data from the first facility andto translate the first data into raw data; and a second utility operableto receive the raw data from the first utility and to translate the rawdata into the second data.
 7. The protocol converter of claim 5, whereinthe first facility, the plurality of cascaded utilities, and the secondfacility run as processes on the protocol converter, the protocolconverter further comprising: a communications subsystem operable tomanage communications among the processes running on the protocolconverter; and a process table coupled to the communications subsystem,the process table having an entry for each process running on theprotocol converter.
 8. The protocol converter of claim 5, wherein: thefirst facility supports at least one of a first link layer and a firstline layer communications protocol; the second facility supports atleast one of a second link layer and a second line layer communicationsprotocol; and each of the plurality of cascaded utilities is operable totranslate the first data using the at least one of the first link layerand the first line layer communications protocol into the second datausing the at least one of the second link layer and the second linelayer communications protocol.
 9. A method for communicating between aremote and a host, the method comprising: receiving, at a firstfacility, first data in a first protocol from the remote; transmitting afirst message from the first facility to a session manager in responseto the first data; spawning the first utility in response to the firstmessage; transmitting a second message from the session manager to thefirst utility; transmitting an acknowledgment to the second message fromthe first utility to the first facility; spawning the second utility inresponse to the first message; transmitting a third message from thesession manager to the second utility; transmitting an acknowledgment tothe third message from the second utility to the first utilitytranslating, at the first utility and the second utility, the first datainto second data in a second protocol; and communicating, at a secondfacility, the second data to the host.
 10. The method of claim 9,wherein: the first facility supports at least one of a first link layerand a first line layer communications protocol; the second facilitysupports at least one of a second link layer and a second line layercommunications protocol; and the first utility is operable to translatethe first data using the at least one of the first link layer and thefirst line layer communications protocol into the second data using theat least one of the second link layer and the second line layercommunications protocol.